flag of truce

a white flag displayed as an invitation to the enemy to confer, or carried as a sign of peaceful intention by one sent to deal with the enemy.

Origin of flag of truce

First recorded in 1620–30

They sent forward a flag-of-truce, and demanded the instant surrender of the stockade.

Camp-Fire and Cotton-Field |Thomas W. Knox
We were expecting almost hourly to be put on a flag-of-truce boat.

The Story of a Strange Career |Anonymous
If we turned for the left it would be for the flag-of-truce boat; if to the right, it meant an indefinite stay in prison.

The Story of a Strange Career |Anonymous
Shortly after the fighting ceased, Colonel Ellet sent the ram Lioness, under a flag-of-truce, to demand the surrender of the city.

Camp-Fire and Cotton-Field |Thomas W. Knox

But when the flag-of-truce party reached the "Horn o' Plenty" they found not a corsair there!

The Bee-Man of Orn and Other Fanciful Tales |Frank R. Stockton

flag of truce

a white flag indicating the peaceful intent of its bearer or an invitation to an enemy to negotiate